A number of prior art patents relate to hard drive covers. Few of these patents use polymeric hard disk cover. Since polymers are generally viscoelastic bodies, the force applied by screws in clamping the hard disk top cover against a seal on bottom base member thereby applying sealing pressure. However, the seal pressure relaxes between the screws locations due to viscoelastic creep thereby relieving the sealing pressure.
U.S. Pat. No. 6,023,392 to Kim discloses a hard disk drive cover having improved structural and production characteristics. The hard disk drive cover is constructed using plastic resin that is injection molded to form the cover. A reinforcing frame is inserted inside the injection molded cover. The reinforcing frame has a plurality of stainless steel elongated bands that extend radically outward to engage a plurality of edges of the cover during injection molding of the polymer cover. Each of the elongated bands has a perforation in a distal end to fasten and engage with the base of the hard drive. Thus, the polymeric injection molded top cover is reinforced with radial stainless steel reinforcing bands. The bands do not reinforce the locations between the screws that affix the top cover to the hard drive base and the gasket in these portions will not receive adequate compression to provide an effective seal.
U.S. Pat. No. 6,407,879 to Fruge', et al. discloses disk drive cover features for spindle resonance tuning and damping. The disk drive has spindle resonance tuning and damping features for improved disk drive performance. The disk drive has slots in the top cover which reduces rocking resonant frequency of the spindle to allow a previously interacting spindle to no longer interact. A constrained-layer damper can be added over the top cover to dampen existing or interacting frequencies, which can further improve performance. This disk cover is provided with a plurality of circular shaped slots in between the spindle location and the periphery of the disk drive cover and the presence of slots prevents coupling of vibrations between the spindle vibrations and vibrations of the top cover thereby preventing resonance amplification. The disk drive top cover may be selected from the group consisting of plastic, aluminum or stainless steel. There are no stiffeners in the disk drive top cover plate between the bolt retaining locations.
U.S. Pat. No. 6,469,864 to Kamezawa, et al. discloses a disk drive having a resin cover improved in electromagnetic protection characteristics. A disk drive includes a housing having a base and a cover fixed to the base. A rotatable disk is mounted in the housing and having a plurality of tracks, a head for reading/writing data on the disk, and an actuator for moving the head across the tracks of the disk. The cover is composed of a molded resin and a metal sheet integrally embedded in the molded resin. The cover is composed of molded resin with a copper or steel metal sheet or mesh integrally embedded within the resin. The metal sheet has a majority of both the upper surface and a lower surface covered by the molded resin of the cover. The cover is secured to the base by a plurality of screws and the metal sheet embedded in the cover is exposed at portions where said screws are located. The screws contact both the metal sheet and the base to providing electromagnetic protection. The metal sheet used is a thin sheet of metal or mesh provided for electromagnetic protection and extends the entire top cover of the hard drive, not just the flange. Being a thin sheet or mesh, it does not provide any significant rigidity to the flange portion of the top cover improving seal performance.
U.S. Pat. No. 6,473,263 to Jung et al. discloses a cover structure of hard disk drive with air damping layer. The cover structure of a hard disk drive (HDD) can optimally suppress noises and vibrations generated in the HDD. The top cover of the disk drive has a damper attached there to with an air gap between the top cover and the damper. The air gap is indicated to provide better damping of spindle generated vibrations. The flange of the top cover does not have metallic reinforcement and the top cover is not indicated to be made from injection molded plastic.
U.S. Pat. No. 6,493,180 to Kang, et al. discloses a hard disk drive cover that contains a Helmholtz resonator which attenuates acoustic energy. A disk drive housing is provided with Helmholtz resonator that can attenuate noise. The housing may include a first layer that is attached to a second layer, and a gap located between the first and second layers. The layers and gap may be configured to attenuate acoustic energy within a relatively broad frequency range. This is a conventional hard drive housing that has its base portion and top portion made as two layers with a gap there between forming a Helmholz attenuator. The top cover or the hard drive is not made from injection molded plastic.
U.S. Pat. No. 6,525,931 to Yagenji, et al. discloses a cover for a hard disk drive. This cover for the hard drive is a laminated two metal plate structure that entirely contains a vibration absorbing resin. The resin prevented from leaking out by bent edges provided in the laminated metal plate structure. At the screw locations, the hole in the marginal (top) plate has bent edges so as to encase the gel. The sealing member contacts the bottom portion of the laminated top plate. The sealing member has nothing to do with the vibration absorbing gel contained within the laminated plate structure. The laminated plates are made from metal and are not formed from injection molded polymer.
U.S. Pat. No. 6,560,063 to Keffeler, et al. discloses a top cover for disk drive having stiffening features and gasket clearance enhancements. The top cover for the disk drive has a skirt that protrudes downward perpendicular to the flange providing increased stiffness, The skirt also creates a space between the bottom plate edge and the protrusion. This space is available for expansion of a compressed gasket that is used for sealing the bottom and top portions of the hard disk drive. All the components are made from metal and the top cover is not made from injection molded polymer.
U.S. Pat. No. 6,567,237 to Iwahara, et al. discloses a sound reducing cover seal for information recording apparatus. The cover seal seals an opening of a housing body and encloses a cover for the opening in cooperation with the housing body. The rigidity of the cover seal is reinforced by a metallic sheet or a multiplayer synthetic resin sheet, so that vibration of the cover seal is prevented even if an air stream between the housing body cover acts on the cover seal from behind. The sound is attenuated by a top cover, which is adhered to the top lid of the hard drive. The hard drive cover is not made from injection molded polymer.
U.S. Pat. No. 6,876,515 to Unno discloses a monolithically constituted gasket assembly with cover and hard disk drive unit. A hard disk drive unit constituted in the following manner can prevent leaks of gas caused by a deformed gasket assembly. The hard drive gasket assembly can enhance operational performances of the hard disk drive unit and can be assembled more easily. The top cover for the hard drive is indicated to be made from aluminum, plastic and the like and has holes in predetermined locations for inserting a gasket, which seals the cover against the base. No bolt or loading structure is indicated to retain the gasket in sealing compression. A ring projection iron protrudes against the base and the gasket also contacts the seal ring. This '515 patent does not address proper loading of the gasket providing a reliable seal.
U.S. Pat. No. 6,900,961 to Butler discloses a disk drive having a head disk assembly enclosure including insert molded components. The disk drive has an injection molded head disk assembly enclosure including insert molded components. A pivot is insert molded into the base. A first portion of a spindle motor is insert molded into the base. A second portion of a spindle motor is attached to the first portion to form the spindle motor. Further, a disk is mounted to the spindle motor and a head stack assembly having a coil portion is pivotally coupled to the pivot. No insert molded reinforcement is provided at the flange.
U.S. Pat. No. 6,950,275 to Ali, et al. discloses a disk drive having cover assembly which compresses a foam member between substantially planar rigid members. The top cover of the disk drive is a planer rigid plate made from stainless steel or aluminum and is not indicated to be made from injection molded polymer. A gasket is placed in between the planar rigid member of the top cover and the planar rigid member of the base and is secured after compressing to a third of its thickness by screws providing vibration absorption. The gasket loading uniformity is not an issue since both the top cover and base are planar rigid members.
U.S. Pat. No. 7,000,309 to Klassen, et al. discloses a method of assembling a disk drive by electrically grounding a disk drive cover. The method of assembling a disk drive includes providing a disk drive base, providing a disk drive cover having an inside face and an outside face. The inside face is coated with an electrically insulating material. The method further includes contacting, continuously during a period, the outside face with an electrically conductive grounding element that is part of an assembly fixture that is not part of the disk drive being assembled. The disk drive cover is made from a metal or conductive plastic. The '309 patent is concerned with providing insulating layers between conductive plates and grounding the outer portion of the conductive top plate. The '309 patent does not address problems of gasket sealing when a low modulus polymeric material is injection molded to create a low cost top cover.
U.S. Pat. No. 7,082,011 to Nakamura discloses a recording medium drive capable of preventing flexure of base and cover. A cover is received on the receiving surface of a base in a recording medium drive. A fastening mechanism serves to couple the cover to the receiving surface. An elastic member is interposed between the receiving surface and the cover. The elastic member is located along the occupied space of the fastening mechanism. The elastic member thus continuously surrounds the occupied space. A compressible gasket material continuously surrounds a screw fastening location thereby exerting uniform forces around the fastening screw preventing bending deformation of the top plate or the bottom base. The deformable gasket also extends between the screws that secure the top cover to the base and the bending of the top cover between the screws will result in leakage. The top cover is not indicated to be an injection molded polymer.
U.S. Pat. No. 7,292,406 to Huang discloses a disk drive including a spindle motor and a pivot bearing cartridge attached to different layers of a laminated cover. The laminated top cover that carries the spindle and the cartridge is not an injection molded polymeric part.
U.S. Pat. No. 7,301,725 to Kim, et al. discloses a disk drive with cover plate having high stiffness. The disk drive comprises a cover plate with preload tension formed across the cover plate for increasing the stiffness of the cover plate. The preload tension is formed across the cover plate after the cover plate that was warped is secured to a base member of the disk drive to become un-warped. Such a cover plate with increased stiffness is not easily deformed and effectively minimizes propagation of noise generated from operation of the disk drive. The top cover plate is made from a high stiffness metal such as stainless steel and is twisted in the pre-loaded condition. Securing this twisted top cover to a flat base results in pre-defined stresses that are indicated to improve sealing at the gaskets. The top cover is not made from an injection molded plastic material.
U.S. Pat. No. 7,385,784 to Berding, et al. discloses a disk drive cover with top and bottom layers electrically grounded with first and second flaps and method of manufacturing the same. The top cover has a top metallic plate, a bottom metallic plate and a viscoelastic material sandwiched between the top and bottom metal layers. Each of the top and bottom metallic plates is provided with tabs for grounding the cover plate. The top cover of the disc drive is not made from an injection molded plastic material.
U.S. Pat. No. 7,420,771 to Hanke, et al. discloses a disk drive with cover including a metal layer and a polymer layer with a polymer layer feature. The top cover of the disk drive has a metal layer and a polymer layer, which may be made from a plurality of individual polymer layers defining cavities. The metallic or polymer layer of the top cover contacts the base of the hard drive. The top cover has continuous metallic sheet and does not provide selective reinforcement of the polymer layers. The top cover is not an injection molded polymeric material with selective reinforcement.
U.S. Pat. No. 7,428,122 to Kimura, et al. discloses a hermetically sealed disk drive with low height. An assembly structure low in height and suitable for downsizing and for high hermeticity sealing in a micro hard disk drive is provided. Burrings projecting toward a top cover and having an internal thread cut are formed on a base plate where the top cover is screw-fastened to the base plate. The top cover is a flat sheet with burrings that are adopted for insertion into the base and secured by screws. The cover is not indicated to be an injection molded top cover.
U.S. Pat. No. 7,450,338 to Hur discloses a hard disk drive cover with protruding blades for reducing disk and HGA vibration. The cover of the hard disk drive has a blades protruding from a surface of the base and/or a portion of the cover facing the disk. The blade guides an airflow caused by rotation of the disk toward an outer edge of the disk. The top cover of the hard disc is not an injection molded polymeric component.
Thus, there remains a need for low cost injection molded top cover for hard drives with a reliable leak proof long life seal at top cover flange eliminating viscoelastic relaxation of the polymeric injection molded top cover flange.